1. Field of the Invention
The present invention relates to a method for manufacturing a module including a planar coil, and a module including a planar coil.
2. Description of the Related Art
For example in Japanese Patent Application Laid-Open No. H7-283029, a printed wiring board with a built-in inductor is proposed. This printed wiring board with a built-in inductor will be described based on FIG. 10. As shown in FIG. 10, a through hole 1a in a predetermined shape is formed in a printed wiring board 1. An annular counterbore section 1b is formed outside the through hole 1a, and an annular insulating wall 1c lies between the counterbore section 1b and the through hole 1a. A coil 2 is mounted on the counterbore section 1b. A winding coated with an insulating film is wound to form the coil 2. Further, a first core member 3a with a plain plate is mounted with respect to the through hole 1a in the printed wiring board 1 from the lower surface side thereof, and a second core member 3b in a planar shape which is opposed to the first core member 3a is arranged on the top surface of the printed wiring board 1. A planar section of the first core member 3a is bonded to the printed wiring board 1, and the second core member 3b is bonded to the first core member 3a and the printed wiring board 1, to unify the first and second core members 3a, 3b as a core 3.
However, in the case of the conventional printed wiring board with a built-in inductor shown in FIG. 10, a significant amount of time and work is required to form the counterbore section 1b in the printed wiring board 1 for the purpose of mounting the coil 2, thereby increasing manufacturing cost of the printed wiring board 1 with a built-in inductor. Further, since the through hole 1a in the printed wiring board 1 is mounted with the first core member 3a which penetrates the through hole and the first core member 3a is joined with the second core member 3b, the core 3 ultimately becomes thick, which is not preferred in a scene where a reduced profile is required. Moreover, since the coil 2 is formed of a winding, it cannot cope with a large current.